| 摘要 |
PURPOSE:To make the circuit integration easy, by using an MOSFET in place of a resistor by giving weight to the ratio of channel width to channel length. CONSTITUTION:Weighting is made so that the ratio of channel width to channel length of Nth MOSFETs 11-14 is (1/2N<-1>) to that of an MOSFET10. That is, taking a current flowing to an FET10 as I0, a current of (I0/2N<-1>) flows to an FET14. Switches S1-SN are controlled with input data, currents flowing to MOSFETs 15-19 are added at an adder 25 to be an analog value according to the input data. Since constant current operation is made for the FETs 10-14 with a comparator 7, no error is caused even to some extent of output resistance of the FETs 15-19. |
